In advertisements published in major newspapers on Sunday, the DPJ confidently predicted: "Today, a government change."
"A courageous decision by the people will open the door for a historic and major event," it said in a separate statement. "Please join in this big task to change Japan and protect the people's lives."
The LDP has ruled for all but 10 months since it was founded in 1955, but the DPJ already controls the less powerful upper house of parliament following elections in 2007.
Tobias Harris, a Tokyo-based political commentator and blogger, said that changes in the two parties over the past four years had worked in favour of the DPJ.
"The LDP has reverted to the party that it used to be and the DPJ has become a much more active party, a much more disciplined party, a party that people could trust with government," he told Al Jazeera.
"If you ask voters they are prepared to trust the DPJ once, but only once.
"The DPJ has really worked at finding candidates who can speak to voters, who are skilled at policy, who actually make the party look young, exciting and vital. That is a big part of the story of why the DPJ is set to win today."
In its advertisements on Sunday, the LDP urged voters: "Don't destroy Japan".
"Hope tomorrow can only come from stability today," it said.
Al Jazeera's Steve Chao, reporting from Tokyo, said that last-minute surveys indicated that the opposition was still on its way to a landslide victory because of dissatisfaction with the current government.
|High turnout is expected among
Japan's 103 million voters [Reuters]
"The economy is in the worst state since the second world war, unemployment is at 5.7 per cent, which means that three and a half million people are unemployed," he said.
"The opposition has been [conducting] on an Obama-style campaign, promising massive changes, to take on the heavy bureaucracy created by the ruling government that is largely blamed for the problems of the country."
But Masura Tamamoto, a senior fellow at the World Policy Institute in Tokyo, said: "People here are voting for the DPJ to change the government so their lives don't have to change.
"There's really no much difference between the LDP and the DPJ, no ideological differences, no vision for a different type of society.
"The change is about government efficiency, its about how well you can run the government, the LDP had its chance for about 20 years and the economy has been going down. People want a secure a predictable life."
Surveys in major newspapers, including the Mainichi and the Asahi, said that the DPJ was likely to win more than 320 seats in the 480-member lower house of parliament.
Hatoyama travelled to the city of Sakai in western Japan on Saturday - the final day of campaigning - where he repeated his call for voters to support change.
"This is an election to choose whether voters can muster the courage to do away with the old politics," he said.
Under a mantra of "Putting People's Lives First", the DPJ has offered a platform heavy on social-welfare initiatives, including cash handouts for job seekers in training and families with children.
Al Jazeera's Chao said that Aso had also come out strongly on Saturday, making a his last-minute appeal to urge voters "to reconsider and to question whether they could trust the opposition to run the government at a time of economic crisis.
"He has also stressed that he needs more time to implement the massive economic reforms to deal with the global financial crisis.
"Japan is the world's second largest economy and that's why it matters a lot, not only to the voters down here but to the rest of the world because what happens in Japan is often a bellwether for the health of the world’s financial status."